Many attempts have been made to solve the problem of supplying oil to an engine under adverse conditions such as long periods of disuse of the engine, low ambient temperature, failure of internal oil pump, etc.
The solutions in the prior art provide a reservoir of oil in a chamber. The reserved oil is forced out of the chamber by a spring loaded piston held by a catch. This reserved oil is provided to critical engine points upon the release of a latch holding the catch. The initiation of this pre-oiling function is ABSOLUTELY DEPENDENT upon the disengagement of the catch from the latch. The latches taught to be used by the prior solutions involve the pulling of the latch from engagement with the spring loaded catch. Thus, the normal static coefficient of friction between the latch and catch is increased by the spring loading of the latch no matter how long the engine has been idle. The pressing of a latch to the catch as taught by the prior art may result in a partial bonding of the parts or at least contribute an additional element of force which must be overcome before the catch is released from the latch.
Further, the prior art teaches that a spring loading of the piston is sufficient to overcome the viscosity of the reserved oil in the chamber even under adverse environmental conditions.
U.S. Pat. No. 2,867,203 attempts to solve the problem by providing a latch/catch configuration in which a rounded latch engages a rounded catch. However, the coefficient of friction is independent of the size or shape of the contact surface. Further, both ends of the latch 25, not just the rounded end, must still overcome the additional friction caused by the spring compression holding the latch against the catch in order for the catch to be released. The release mechanism is a solenoid. The use of a solenoid introduces yet another degree of difficulty in that the pulling force generated by a solenoid is at its weakest when the core is positioned remote from the coil. Thus, some solutions require the solenoid to overcome the coefficient of static friction by withdrawing the core from its weakest attraction, most extended position. Either a large solenoid current must be supplied or a larger solenoid must be incorporated to practice the solutions taught by the prior art to overcome this initiation force.
U.S. Pat. No. 4,112,910 ('910) offers a solution which still requires the initiation of a solenoid at an extended position to move a tripping plate 49 and locking rollers 37 used as a latch in contact under spring loaded locking head 30 before the spring loaded piston of the device delivers oil in the chamber to the vehicle engine. '910 also teaches outfitting the device with a heater to raise the temperature of the oil to allow user to operate the device under changing environmental conditions. The incorporation of a heater requires even more energy to initiate starting of the vehicle and the addition of a heater could become a potential fire hazard should the oil heater malfunction.
Thus there has long been a need for an arrangement utilize a positive, minimal friction and minimal inertia release actuator to initiate a rise in oil pressure rather than a catch within latch release which must overcome a relatively high coefficient of static friction increased by using a spring loaded catch, especially after a long term of disuse.
Further, it is also desired that, in order to allow positive release of a spring loaded piston to initiate delivery of oil, the latch holding the piston be configured with the minimum of mass and without the need to pull the latch from contact with the catch.
Further, it is also desired that, in order to assure flow of the oil even in adverse environmental conditions, the device provide some variable compensation other than adding heat energy to the oil resevor.
Further yet, it is also desired to provide for low power initiation of movement of the catch to release the latch by means of a solenoid in order to compensate for a weak battery in any engine which has been sitting idle for a while.
Yet further, it is desired to provide a device which will react to the variations of oil pressure internal to the engine and provide a more even level of oil pressure to the critical parts of the engine.